No storm in a teacup


No storm in a teacup

What happens when you stir a superfluid? Able to flow without resistance, superfluids respond by forming quantized vortices – tiny storms that interact with each other to create quantum turbulence.

Due to its complexity, turbulence is one of the persistent enigmas in Physics. In superfluid helium there is a further challenge: the vortices are so small that measuring the chaos they create is technically challenging. This challenge also offers an advantage as helium can hold a lot of vortices, providing a fertile platform for the study of fully-developed quantum turbulence.

Using a new nondestructive measurement protocol, the experimental group of Professor Warwick Bowen at the University of Queensland were able to track vortices in thin films of turbulent superfluid helium-4. Sachkou et al. developed a technique for the nondestructive tracking of vortices in a thin film of superfluid helium-4. Their system contained a microtoroid optical cavity coated by a thin film of helium-4. Vortices were created and measured using laser light that can efficiently couple into the cavity. Surprisingly, coherent vortex dynamics were found to strongly dominated over dissipation by five orders of magnitude. The on-chip platform provides a new way to study emergent phenomena in strongly interacting superfluids, and to develop quantum technologies such as precision inertial sensors.

Theory collaborator, Dr Ashton Bradley of the Dodd-Walls Centre says “…this experiment opens up new territory for fundamental understanding of quantum turbulence, and also has potential applications in high precision sensing… exciting progress in a challenging field.”

The research was a collaboration between researchers in the ARC Centre of Excellence for Engineered Quantum Systems (EQUS) and ARC Centre of Excellence in Future Low-Energy Electronic Technologies (FLEET) in Australia, and the Dodd-Walls Centre for Photonic and Quantum Technologies in New Zealand. It was supported by the United States Army Research Office and the Australian Research Council, and and was published in the journal Science.